Generally, polarizing lenses block polarized light generated when natural light is reflected, and are therefore used for their anti-glare effects or light reducing effects. In recent years, taking advantage of such effects of polarizing lenses, they have been used particularly for protection from polarized light outdoors, for example for protection against polarized light reflected from snow surfaces at a ski resort, or protection from diffuse reflection from water surfaces during fishing, or for protection against reflected light from oncoming cars when driving a car. Additionally, in other fields, polarizing lenses are used for many things, including sunglasses and fashion glasses with the objective of reducing light.
As a transparent resin constituting these polarizing lenses, diethylene glycol bis(allyl carbonate) resin, being a resin with a lower specific gravity than glass at 1.32, having excellent heat resistance, water resistance, solvent resistance, and workability, and further having vision correction effects, and still further optimal for productivity of small quantities of diverse products, is primarily used. Diethylene glycol bis(allyl carbonate) resin polarizing lenses are generally manufactured by the method (cast polymerization) described in Patent Publication 1, wherein, after fitting molds into both sides of a gasket, and placing a polarizing film between the two molds, the space is filled with diethylene glycol bis(allyl carbonate) monomer wherein a polymerization initiator has been mixed and dissolved, and the monomer is cured by polymerization. Alternatively, there are cases where polarizing lenses are manufactured by adhesively joining together two lenses with a polarizing film sandwiched in between, as described in Patent Publication 2.
[Patent Publication 1] Japanese Unexamined Patent Publication No. S61-235113
[Patent Publication 2] Japanese Unexamined Patent Publication No. 2001-249227